For reasons of economy and in order to reduce the environmental impact of materials usage, there is a growing trend towards the use of refillable devices of various kinds rather than the use of disposable devices. In many cases it is of no great concern how many refill units have been used with a particular device. However, other devices may have a limited life span in the interests of device efficiency, consumer protection, hygiene, manufacturer's liability etc.
U.S. Pat. No. 5,950,016 discloses a recyclable camera and film combination in which the camera comprises means for automatically rewinding the film after the last frame in the film has been shot, means for controlling the lid so as to automatically open when the entire film is rewound into the film cartridge, means for counting the number of film cartridges loaded into the cartridge chamber, and means for making the controlling means inoperative, whereby the lid does not open for the removal of the film cartridge loaded in the cartridge chamber when the counting means reaches a predetermined number of film cartridges and thus prevent the cartridge chamber from receiving any further film cartridges.
U.S. Pat. No. 5,659,837 discloses a developing device in an image forming apparatus having a cartridge loading portion for loading a replaceable toner cartridge, a frame including a hollow portion for receiving a developer supplied from the cartridge. A photosensitive drum installed in the hollow portion and having a surface exposed to the exterior of the frame, and a developer roller installed adjacent to the photosensitive drum, the developing device having a cartridge control device installed on the one side of the cartridge loading portion to control the installation and removal of the toner cartridge in which the cartridge control device includes a cartridge installation and removal device for allowing a user to install or remove the toner cartridge, a counter for counting the number of toner cartridge replacements, and a cartridge removal protector for prohibiting removal of the toner cartridge from the developing device when a predetermined number of toner cartridge replacements is reached so as to prevent contamination resulted from an imbalance between the total amount of the toner supplied and the capacity of a waste toner container.
WO92/17231 discloses a medical inhaler featuring a microelectronic assembly, a receptacle for a container of medication, a triggering element electrically coupled to the microelectronic assembly, positioned inside the receptacle and activated by pressing the container to release a dose of medication. The microelectronic assembly may be a counter, or an interval timer for recording the dosage history of the container, including time intervals between doses. The inhaler includes electrical contact fingers contacting an electrical circuit on the container which stores information about the container in digital form. The digital data storage means includes a set of electrically conductive strips on the container whose spatial pattern represents data about the container and a microelectronic memory. The digital data stored includes the number of doses remaining, the time interval between doses previously actuated, the type of medication, the expiration data, the lot and serial number of the container and other usage information.
In the medical field there are a range of refillable devices, e.g. for the delivery of medicament, saline etc., to a patient which would benefit from a simple, effective system of recording how many refill units have been used with a particular device. It would also be advantageous for the device to be disabled after a predetermined number of refill units have been used.